Apparatus and method for holding materials for the forming and joining thereof

ABSTRACT

A machine cell for the forming and joining of a first sheet material to a second sheet material includes an upper gate and a lower nest. The lower nest includes a vacuum pad having a recessed channel defined therein. A vacuum system is fluidly connected to the recessed channel to hold the first sheet material to the lower nest during the joining of the first and second sheet materials. The machine cell further includes an arrangement for aligning the first sheet material to the second sheet material.

RELATED APPLICATION

This patent application is a continuation-in-part of pending U.S. Ser.No. 10/521,655 filed Jan. 14, 2005.

FIELD OF THE INVENTION

The present invention relates to systems for holding and aligning afirst sheet material and a second sheet material for the joiningthereof. More particularly, the present invention relates to a methodand apparatus for holding a first sheet material and a second sheetmaterial that utilizes a vacuum arrangement for holding the first sheetmaterial in place during the alignment of the second sheet materialthereto and during the joining of the first sheet material to the secondsheet material.

DESCRIPTION OF THE RELEVANT ART

One of the earliest operations required in the history of automobileassembly was the joining of an inner panel to an outer panel to form anyof a variety of body parts, including doors, engine hoods, fuel tankdoors and trunk lids, all referred to as “swing panels” which encase thevehicle frame. Known machines for the forming and joining of sheetmaterials include the press-and-die set, the tabletop and theroller-forming tool, the latter being the most-recently introduceddevice.

An unfortunate feature of joining materials is that the sheets tend tobecome misaligned with each other before or during the joiningoperation. Certain efforts have been undertaken to overcome thisproblem.

One known effort employed to prevent the skidding of one sheet relativeto the other has been to apply an upper pressure ring from above thesheet materials, thereby pinching the upper and lower sheets between theupper pressure ring and the lower nest member. This practice leads tothe consumption of much of the workspace above the sheet materials. Inaddition, the use of the upper pressure ring requires a high-poweredoverhead device to effect operation. All considered, the use of theupper pressure ring is costly and inconvenient.

An additional known practice to prevent skidding of two sheets duringjoining is to align the two sheets relative to one another from the sideusing side gauges. This operation, while offering certain advantagesover the use of the upper pressure ring in terms of cost, space andequipment, does a poor job of controlling movement of the sheetmaterials. The use of gauges also leads to defacing of the sheetmaterial through scratching during loading and unloading of the sheetmaterial. Importantly, during operation, the gauges interfere with thetravel of the forming tool. In some instances, if the gauges arespring-loaded, the rolling tool may be shocked and may suffer a pressurebounce when struck.

An additional practice has been to simply position one sheet above theother without holding, this latter approach clearly being the leastdesirable.

Prior to the invention of the method and apparatus disclosed inco-pending U.S. Ser. No. 10/521,655, prior approaches to the problem offorming and joining two sheet materials together while restrictingmovement of the sheets relative to one another had failed. Whileimproving the state of the art, the method and apparatus of co-pendingU.S. Ser. No. 10/521,655 still had remnant sheet material movement.Furthermore, even with that improvement, the manufacturing of the vacuumchamber(s) is tedious and repair difficult.

Accordingly, prior approaches to solving the problem of providing amethod and apparatus for forming and joining two sheet materialstogether while restricting movement of the sheets relative to oneanother have failed to overcome the problem.

SUMMARY OF THE PRESENT INVENTION

It is thus the general object of the present invention to streamlinemanufacturing set forth in U.S. Ser. No. 10/521,655 and improve itseffectiveness. The manufacturing accuracy increases as a computernumerically controlled mill can cut grooves into the hard top surfacethat comprise the vacuum chambers. This streamlines manufacturing incomparison to the molded chambers of U.S. Ser. No. 10/521,655 as theyare not used and the spotting if the molds is no longer required.

It is thus an additional general object of the present invention toprovide a method and apparatus that overcomes the problems of knowntechniques for forming and joining a first sheet material to a secondsheet material to create a swing panel for an automobile.

It is a particular object of the present invention to provide a machinecell for forming and joining a first sheet material to a second sheetmaterial which provides a definite method for aligning and securing afirst panel to the lower nest and for aligning and securing the secondpanel to the first panel.

A further object of the present invention is to provide such a machinecell which utilizes an array of crowders to align the first panel on thelower nest.

Yet another object of the present invention is to provide such a machinecell which utilizes a vacuum system to securely hold the first panel tothe lower nest.

Still a further object of the present invention is to provide such amachine cell which utilizes an upper gate for aligning and holding thesecond panel relative to the first panel.

Another object of the present invention is to provide such a machinecell which is efficient, cost-effective, and flexible enough toaccommodate panels of various sizes, shapes, and contours.

These and other objectives are achieved by the provision of a machinecell which includes an upper gate and a lower nest. The lower nestincludes an upper surface which has at least one channel defined in theupper surface. A vacuum source is fluidly connected to the channel(s).

A pair of married sheet materials A, B are approximated onto the lowernest. The first sheet material A is then precision positioned by meansof crowders. The upper gate thereafter aligns the second sheet materialB with respect to the first sheet material A by alignment pins. Thefirst sheet material A is held in place by a vacuum applied to its underside by way of the channel. Thus held in place, a forming operation maybe effected for joining the first sheet material A to the second sheetmaterial B.

In addition, the present invention provides a machine cell for formingand aligning a first sheet material to a second sheet material whilerestricting movement of the sheets relative to one another as set forthin U.S. Ser. No. 10/521,655.

These and other objectives are accomplished by the provision of amachine cell for forming and aligning a first sheet material to a secondsheet material as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more fully understood by reference to thefollowing detailed description of the preferred embodiments when read inconjunction with the accompanying drawings, in which like referencecharacters refer to like parts throughout the views, and in which:

FIG. 1 is a perspective view of the preferred embodiment of the presentinvention;

FIG. 2 is a sectional view taken along lines 2-2 of FIG. 1;

FIG. 3 is a perspective view of the upper gate of the present invention;

FIG. 4 is a sectional view of a spring plunger according to the presentinvention;

FIG. 5 is a top plan view substantially illustrating a sample innersheet material or the support structure that forms the inner part of theresulting joined component;

FIG. 6 is a perspective view substantially illustrating the top of thelower nest member;

FIG. 7 is a perspective view substantially illustrating the top of thelower nest member; and

FIG. 8 is a sectional view taken along lines 4-4 of FIG. 7;

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION

The drawings disclose the preferred embodiment of the present invention.While the configurations according to the illustrated embodiment arepreferred, it is envisioned that alternate configurations of the presentinvention may be adopted without deviating from the invention asportrayed. The preferred embodiment is discussed hereafter.

With reference first to FIG. 1, the preferred embodiment of a machinecell, generally referred to as 10, is illustrated in a perspective view.The machine cell 10 includes an upper gate 100 and a lower nest 200. Itshould be understood that the configuration of the machine cell 10 asillustrated is preferred, but is not to be interpreted as limiting asother configurations conceivable to those skilled in the art may also besuitable.

The present invention serves to hold two portions of sheet material sothat a joining process may be undertaken without the sheet materialportions being caused to shift or otherwise move out of position. Thetwo portions of sheet material include a first sheet material A and asecond sheet material B. The two sheets A and B, in a combinationresulting from joining and forming becomes an integrated component, ofwhich the first sheet material A is the outer part or the skin and thesecond sheet material B is the inner part or the support structure.(This latter material is illustrated, by way of example, in FIG. 5,discussed below.) As illustrated, the first sheet material A and thesecond sheet material B have a generally square configuration resultingin a generally square-shaped integrated component. However, it is to beunderstood that other shapes may be suitable for use in the presentinvention.

In brief, the married sheet materials A, B are approximated onto thelower nest 200. The first sheet material A is then precision positionedby means of crowders, which will be discussed below primarily inrelation to FIG. 1. Thereafter the upper gate 100 aligns the secondsheet material B with respect to the first sheet material A by alignmentpins as will be discussed below primarily in relation to FIG. 3. Thefirst sheet material A is held in place by a vacuum applied to its underside. Thus held in place, a forming and joining operation may beeffected for clinching the first sheet material A to the second sheetmaterial B.

The upper gate 100 is shown in perspective view in relation to theentire machine cell 10 in FIG. 1, in sectional view in FIG. 2, and byitself in perspective view in FIG. 3. As illustrated in these figures,the upper gate 100 includes a main shaft 102 that is attached to arobotic arm or linear slide attachment shaft 101. The main shaft 102 isfixed in a substantially perpendicular position with respect to therobotic arm attachment shaft 101.

Pivotally attached to the main shaft 102 are three substantiallyparallel contact plunger support shafts 104, 104′, 104″. Each of theplunger support shafts 104, 104′, 104″ is attached to the main shaft 102by a lockable swivel joint illustrated as lockable swivel joints 106,106′, 106″. The lockable swivel joints 106, 106′, 106″ allow the supportshafts 104, 104′, 104″ to be rotated with respect to the main shaft 102thereby accommodating a variety of panels of different sizes and shapes.The composition of the shafts 102, 104, 104′, 104″ may be from a rangeof materials, including steel or aluminum.

Each of the plunger support shafts 104, 104′, 104″ preferably includesat least two contact plunger assemblies for firmly urging the secondsheet material B against the first sheet material A. Specifically,contact plunger assemblies 108, 108′, 108″ are rotatably attached to theplunger support shaft 104, plunger assemblies 110, 110′ are rotatablyattached to the plunger support shaft 104′, and plunger assemblies 112,112′, 112″ are rotatably attached to the plunger support shaft 104″.

Each of the contact plunger assemblies 108 . . . 108″, 110, 110′, 112 .. . 112″ includes a plunger body and an attachment shaft. Using plungerassembly 108′ as an example and as illustrated in FIG. 4, a plunger body114 is pivotally attached to a plunger attachment shaft 116, with theshaft 116 being rigidly fitted to the rotatable plunger support shaft104. It should be noted that while in operation the rotatable plungersupport shaft 104 is locked to the swivel joint 106. However, prior tooperation, the swivel joint 106 may be loosened and the rotatable shaft104 may be rotatably adjusted as needed to provide precise support forthe second sheet material B.

Referring to FIG. 4, in addition to the plunger body 114, the plungerassembly 108′ includes a plunger unit 118 which is preferablythread-fitted into the plunger body 114 thus allowing adjustability withrespect to the plunger body 114. To safely yet firmly urge the secondsheet material B against the first sheet material A, each plunger unit118 includes a spring-loaded nose 119. The nose 119 may be made of avariety of materials, but is preferably made from a hard, non-marringmaterial such as nylon. The plunger unit 118 could be of the typeavailable from the VIier Company of Brighton, Mass.

In addition to the function of applying pressure to urge the secondsheet material B against the first sheet material A, the upper gate 100also preferably provides an alignment function to align the second sheetmaterial B with respect to the first sheet material A. The alignmentfunction is accomplished by alignment pins acting in conjunction withcircular and elongated alignment holes defined in the sheet material (inthis case, sheet material B), which defines the inner part or thesupport structure of the resulting joined component. As illustrated inFIG. 3, certain ones of the plunger assemblies include alignment pinsfor engagement with the circular and elongated alignment holes of sheetmaterial B. According to the preferred embodiment, the plungerassemblies 108 and 110′ each include alignment pins 120, 120′respectively. The alignment pins 120, 120′ include generally conical orpointed ends and function to engage alignment holes a and b shown in thesample second sheet material B illustrated in FIG. 5. It should beunderstood to one skilled in the art that the placement and number ofalignment holes may be varied according to need.

The lower nest 200 is partially illustrated in perspective view in FIG.1 in conjunction with the upper gate 100, is illustrated in sectionalview in FIG. 2 as taken along lines 2-2 of FIG. 1, and is shown inperspective view in FIG. 6 without the upper gate 100, or sheetmaterials A and B.

Referring then to FIGS. 1, 2 and 6, the lower nest 200 generallyincludes a frame 202 and a vacuum assembly 204. The frame 202, alsoknown as an anvil, is configured so as to provide maximum support to thevacuum assembly 204, thus any one of a variety of configurationssuitable for providing needed support may be adapted as known to oneskilled in the art. The configuration shown is for illustrative purposesonly. The frame 202 may be made from a variety of rigid materials,ranging from hard polymers to steel. The frame 202 includes an uppersurface area 206 which provides support during the forming operation ofthe first sheet material A with the second sheet material B as is knownin the art and as discussed further below with respect to the operationof the machine cell 10.

The vacuum assembly 204 includes one or more vacuum pads 208. Each ofthe vacuum pads 208 includes a series of vacuum channels 210, 210′,210″, 210′″. This preferred arrangement allows for the appropriatedegree of vacuum to be applied to the first sheet material A whenpositioned on the vacuum pads 208. While it is possible that otherarrangements may be applied, such as a series of vacuum holes formed ina substantially solid nest surface or a series of vacuum cups, theillustrated arrangement of the vacuum channels 210, 210′, 210″, 210′″ ispreferred. Each of the vacuum pads 208 has an upper surface that isshaped to the contour of the first sheet material A.

Each vacuum pad 208 has a dual purpose—first, to provide a substantiallyair-tight seal with respect to the first sheet material A and, second,to provide a cushioned surface support for carefully supporting thefirst sheet material A while preventing its deformation. Accordingly, itis preferred that the vacuum pads 208 be composed of an elastic orsemi-elastic polymerized material suitable for these purposes.

In addition to the vacuum pads 208, the vacuum assembly 204 includesnecessary elements appropriate to the creation of a working vacuumwithin the channels 210, 210′, 210″, 210′″. FIG. 2 illustrates thepreferred arrangement of vacuum lines for operation of the machine cell10. A vacuum source, generally illustrated as 212, is provided and canbe any one of such known sources. The source 212 is fluidly connected toa centrally located plenum 214. A series of vacuum lines 216, 216′,216″, 216′″, respectively fluidly connect the plenum 214 with the vacuumchannels 210, 210′, 210″, 210′″.

Alignment of the second sheet material B with respect to the upper gate100 is discussed above and is accomplished by use of alignment pins andalignment holes. Alignment of the first sheet material A with respect tothe lower nest 200 may also be accomplished. To make the preferredalignment, two or more crowder assemblies 300, 300′, 300″, 300′″ areprovided on the lower nest 200 to correctly align the sheet material A.Each of the crowder assemblies 300, 300′, 300″, 300′″ includes a movablealignment finger to effect alignment. Using the crowder assembly 300′ asan example, a finger 302 is pivotally provided and is movable between asubstantially vertical aligning position, as shown in FIGS. 1 and 4 anda substantially horizontal disengaged position, as shown in FIG. 2.

The crowder assemblies 300, 300′, 300″, 300′″ are pneumatically operatedand are each fluidly connected to two pressure sources, one for movingthe finger into its substantially vertical aligning position and one formoving the finger into its disengaged position. By way of example, thecrowder assembly 300 is fluidly connected to a first air pressure source304 by a fluid line 306 which operates to hold the finger in itsdisengaged position. A second air pressure source 308 is connected tothe crowder assembly 300 by a fluid line 310 which operates to hold thefinger in its aligning position.

Forming and joining of the first sheet material A with the second sheetmaterial B is accomplished by a known forming unit. As illustrated inFIG. 2, a die/tabletop steel-type-forming unit 400 may be used.Alternatively, or in addition, a roller-tool type of forming unit 402may accomplish the operation of forming and joining. Detail as to theconfigurations of the forming units 400, 402 will be omitted as such iswell known to those skilled in the art.

With reference FIG. 6 and FIG. 7, the two figures have a similar lowernest 200 that generally includes a frame 202 and an upper surface area206 which provides support during the forming operation of the firstsheet material A with the second sheet material B as is known in theart. They also have similar crowders 300, 300′, 300″, and 300′″.

With reference to FIG. 2 and FIG. 8, the upper gate 100 is similar,including components 101, 102, 106, 106′, 106″, 112′ and 120′. Alsodie/tabletop steel-type-forming unit 400 and roller-tool type formingunit 402 accomplish their operation of forming and joining similarly.

The vacuum assembly 204 includes one or more vacuum pads 208. Each ofthe vacuum pads 208 includes a series of vacuum channels 210, 210′,210″, 210′″. The present invention presents a relieved surface 402 thatis offset from the panel A surface approximately equal to the radius ofropes 404 and 406. The ropes 404 and 406 are of urethane or similarlyelastic material. The relieved surface 402 has grooves 408 cut into itapproximately equal to the radius of the ropes 404 and 406. The ropes404 and 406 are laid in grooves 408 and adhered. The top of the exposedropes 404 and 406 are thus in net contact with panel A throughout itslength. A vacuum source is fluidly connected through hole 410. Theperipheral rope 404 forming a closed shape acts as an air-tight seal andthe inner rope(s) 406 acts as a support for the panel to prevent paneldeformation.

Each rope 404 and 406 thus has an upper surface that is shaped to thecontour of the first sheet material A. The ropes rest or are permanentlyglued into the grooves machined into the stiff lower nest material,generally metal, however other stiff materials work as well such asresins and plastics. This configuration makes the vacuum holdingcharacteristics more ridged than the pads 208, permitting much lessmovement when side loading the panel A.

Operation

The operation of the machine cell 10 will now be generally described. Asthe operation begins the upper gate 100 should already be in itselevated position, assuming that a joining operation has already beencompleted and the joined part has been removed, thus leaving the lowernest 200 empty.

Initially a known quantity of mastic is applied to the approximatesurface areas at which the first sheet material A will be joined to thesecond sheet material B. The mastic is utilized to provide a morecomplete joining of the sheet materials. The mastic may be joined to oneof the sheets or to both as may be desired. Known mastics may includeglass bead-filled compositions as are known in the art.

The machine cell 10 may then be operated by a human operator or by aprogrammable logic controller as is known in the art. Regardless of theform of the operator, reference shall be made hereafter generically to“the operator.”

Once the mastic has been selectively applied to the sheets A and B, theoperator marries the first sheet material A to the second sheet materialB then places the combined sheets on the vacuum pads 208 with the firstsheet material A face down (that is, the outer surface of the sheetmaterial A is placed onto the vacuum pads 208). The crowder assemblies300, 300′, 300″, 300′″ are then activated by operation of the second airpressure source 308 to advance the alignment fingers to their engagedand aligning positions. So engaged, the first sheet metal A is inalignment relative to the lower nest 200. This arrangement facilitatespositive micro positioning of the first sheet material A.

The operator then engages the robotic arm or linear slide (neithershown) to lower the upper gate 100 into an engaged position. The roboticcontrol provides that movement of the upper gate 100 with a preciseattitude. As the upper gate 100 is lowered, the alignment pins 120, 120′having generally conical or pointed tips as illustrated in FIG. 3 engagethe circular and elongated alignment holes a and b of the sheet materialB. The pointed configurations of the alignment pins allow for somedegree of initial play with the fit becoming tighter as the upper gate100 is lowered. Accordingly, as the upper gate 100 is lowered, the pins120, 120′ effect alignment by their engagement with the alignment holesa and b.

As the upper gate 100 is lowered and the alignment pins 120, 120′ engagethe alignment holes a and b, the second sheet material B is moved intoalignment with the first sheet material A. The polymerized noses of thecontact plunger assemblies 108 . . . 108″, 110, 110′, 112 . . . 112″apply a light pressure about the periphery of the second sheet materialB, thus ensuring that the first sheet material A is nested onto thevacuum pads 208.

After the first sheet material A and the second sheet material B are inposition, the vacuum source 212 is activated to provide a vacuum betweenthe surface of the first sheet material A and the vacuum channels 210,210′, 210″, 210′″. The first sheet material A is thus immobilized. Withthe combined assembly of the first sheet material A and the second sheetmaterial B secured within the machine cell 10, the first air pressuresource 304 is activated and the fingers of the crowder assemblies 300,300′, 300″, 300′″, 300′″ are drawn away from their aligning positions tothe substantially horizontal positions illustrated in FIG. 2. Thuspositioned, the fingers will not interfere with the subsequent formingoperation.

The joining operation then occurs, by which the upstanding flanges ofmaterial A are formed over onto material B resulting in clinchedformation c. Formation c thus resides around part of or the entireperiphery of the joined first sheet material A and the second sheetmaterial B. As noted above, joining of the first sheet material A withthe second sheet material B is accomplished by either the die/tabletopsteel-type-forming unit 400 or the roller-tool-type-forming unit 402.Regardless of the chosen forming unit, the surface 206 of the frame 202provides a rigid surface upon which forming operations may take place.

Once forming and joining of the first sheet material A to the secondsheet material B is complete, the upper gate 100 is removed from thesecond sheet material B and the vacuum source 212 is de-energizedcausing the first sheet material A to be re-mobilized from the vacuumpads 208. The joined sheet materials A and B are unloaded from the topof the vacuum pads 208 and the next pair of married sheet materials Aand B. is loaded. The forming and joining operation is thus repeated.

Those skilled in the art can now appreciate from the foregoingdescription that the broad teachings of the present invention can beimplemented in a variety of forms. Therefore, while this invention hasbeen described in connection with the particular examples thereof, thetrue scope of the invention should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, specification and following claims.

1. An apparatus for forming and joining a first sheet material to asecond sheet material, the first sheet material having a periphery, theperiphery having a contour, the apparatus comprising: a nest for holdingthe first sheet material, said nest including a material-contactingportion, said material-contacting portion being defined to substantiallycooperate with the contour of the periphery of the first sheet material;a forming and joining assembly operatively associated with said nest,said assembly including a robotic arm and a positional pressure rollertool, said positional pressure roller tool including a roller whichforms and joins the first sheet material to the second sheet material byrolling the first sheet material and the second sheet material betweenthe nest and the roller; and a computer having a roller tool-drivingprogram, said computer being operatively associated with said formingand joining assembly, said computer being pre-programmed with a programprior to the undertaking a forming and joining operation, the programcontrolling the distance between said robotic arm and said nest.
 2. Theapparatus of claim 1 further including a biasing element for biasingsaid positional pressure roller tool against the second sheet materialand the first sheet material during the forming and joining of the firstsheet material to the second sheet material.
 3. The apparatus of claim 2wherein said biasing element is a spring.
 4. The apparatus of claim 2wherein said biasing element comprises a gas-charged cylinder.
 5. Theapparatus of claim 1 wherein said positional pressure roller toolincludes a main roller and a touch-up roller.
 6. The apparatus of claim5 wherein said main roller and said touch-up roller share a common hub,said common hub being rotatably attached to said robotic arm.
 7. Theapparatus of claim 5 wherein said touch-up roller includes a tool insertaperture and an interchangeable tool insert.
 8. The apparatus of claim 7wherein said touch-up roller further includes ball lock for selectivelyengaging said interchangeable tool insert.
 9. A method for forming andjoining a first sheet material to a second sheet material, the firstsheet material having a periphery, the periphery having a contour, themethod comprising: forming an apparatus comprising a nest, a robotic armoperatively associated with said nest, a positional pressure roller tooloperatively associated with said robotic arm, and a controller;pre-programming said controller with a roller tool-driving program thatcontrols the distance between said robotic arm and said nest, saidpre-programming being done prior to the undertaking a forming andjoining operation; holding a first sheet material in said nest such thata periphery of said first sheet material is supported on a materialcontacting portion of said nest; placing a second sheet material on topof said first sheet material; locating said robotic arm having saidpositional pressure roller tool having a roller relative to said nestsuch that said roller engages a flange extending from said periphery;and manipulating said robotic arm to move said positional pressureroller tool along a tool path such that said roller forms said flangeover a periphery of said second sheet material, wherein the position ofsaid robotic relative to the nest dictates an applied pressure betweensaid roller and said material contacting portion.
 10. The method ofclaim 9 further comprises executing said roller tool-driving program ina controller for manipulating said robotic arm such that said appliedpressure is varied along said tool path by positioning said positionalpressure roller tool relative to said material contacting portion in adirection normal to said tool path.
 11. The method of claim 9 whereinsaid partial pressure roller tool has a second roller, said methodfurther comprising: re-locating said robotic arm such that said secondroller engages said flange extending from said periphery; andmanipulating said robotic arm to move said positional pressure rollertool along a second tool path such that said second roller forms saidflange over a periphery of said second sheet material.
 12. The method ofclaim 11 wherein a portion of said first tool path overlaps with aportion of said second tool path such that said roller performs aninitial forming operation and said second roller performs a subsequentforming operation.
 13. The method of claim 11 wherein said first toolpath is distinct from said second tool path such that said roller formsa first portion of said flange and said second roller forms a secondportion of said flange.
 14. The method of claim 9 further comprisingdispensing a mastic on at least one of said first sheet material andsaid second sheet material such that said first sheet material adheresto said second sheet material when formed and joined.